ongoing

Compared meaning: currently happening or in progress (adjective).

比较义项：进行中的（形容词）。

• underway

  Used almost only as a predicate (be/get underway), often after 'already', meaning something has started and is now moving forward; it does not usually modify a noun directly.

  几乎只作谓语用（be/get underway），常跟在“already”后面，表示事情已经开始并在推进；通常不直接放在名词前作定语。

  The construction project is already underway near the old bridge.

  旧桥附近的建设项目已经在进行中了。

• ongoing 本词

  Freely used before a noun (an ongoing investigation) and stresses that something keeps continuing without stopping, sometimes hinting it has dragged on for a while.

  可以自由地放在名词前作定语（an ongoing investigation），强调事情持续不断，有时暗示已经拖了一段时间。

  There's an ongoing investigation into the accident.

  针对这起事故的调查仍在进行中。

Both mean currently happening. Underway is used mainly as a predicate, as in 'be underway' or 'get underway', often with 'already', showing something has started moving. Ongoing is used before a noun, as in 'an ongoing investigation', stressing that something keeps continuing without stopping.

underway 和 ongoing 都表示“进行中的”，但 underway 几乎只作谓语用（be/get underway），强调事情已经开始推进，常与“already”搭配；ongoing 则可以直接放在名词前作定语（an ongoing investigation），强调持续不断，有时暗示事情已经拖了一段时间。